Add compat bits for libtls on Windows

tls/compat/ftruncate.c

@@ -0,0 +1,13 @@
+/*
+ * Public domain
+ *
+ * Kinichiro Inoguchi <inoguchi@openbsd.org>
+ */
+
+#include <unistd.h>
+
+int
+ftruncate(int fd, off_t length)
+{
+	return _chsize(fd, length);
+}

tls/compat/getuid.c

@@ -0,0 +1,14 @@
+/*
+ * Public domain
+ *
+ * Kinichiro Inoguchi <inoguchi@openbsd.org>
+ */
+
+#include <unistd.h>
+
+uid_t
+getuid(void)
+{
+	/* Windows fstat sets 0 as st_uid */
+	return 0;
+}

tls/compat/pread.c

@@ -0,0 +1,23 @@
+/*
+ * Public domain
+ *
+ * Kinichiro Inoguchi <inoguchi@openbsd.org>
+ */
+
+#include <unistd.h>
+
+ssize_t
+pread(int d, void *buf, size_t nbytes, off_t offset)
+{
+	off_t cpos, opos, rpos;
+	ssize_t bytes;
+	if((cpos = lseek(d, 0, SEEK_CUR)) == -1)
+		return -1;
+	if((opos = lseek(d, offset, SEEK_SET)) == -1)
+		return -1;
+	if((bytes = read(d, buf, nbytes)) == -1)
+		return -1;
+	if((rpos = lseek(d, cpos, SEEK_SET)) == -1)
+		return -1;
+	return bytes;
+}

tls/compat/pwrite.c

@@ -0,0 +1,23 @@
+/*
+ * Public domain
+ *
+ * Kinichiro Inoguchi <inoguchi@openbsd.org>
+ */
+
+#include <unistd.h>
+
+ssize_t
+pwrite(int d, const void *buf, size_t nbytes, off_t offset)
+{
+	off_t cpos, opos, rpos;
+	ssize_t bytes;
+	if((cpos = lseek(d, 0, SEEK_CUR)) == -1)
+		return -1;
+	if((opos = lseek(d, offset, SEEK_SET)) == -1)
+		return -1;
+	if((bytes = write(d, buf, nbytes)) == -1)
+		return -1;
+	if((rpos = lseek(d, cpos, SEEK_SET)) == -1)
+		return -1;
+	return bytes;
+}